In general, in agricultural and horticultural fields, a fertilizer for growth promotion of fruits, vegetables, and the like or an agricultural chemical for extermination of pests is diluted with water and sprayed with no additives. However, when the fertilizer or agricultural chemical is diluted with water and sprayed onto plants with no additives, an active component of the fertilizer or agricultural chemical runs off due to rainfall or the like or is released or detached due to wind, which may often impair sustentation of effects.
Accordingly, in order to improve adhesion ability or fixation ability of the active component in the fertilizer or agricultural chemical to a plant, a spreading agent is usually added to a solution obtained by diluting the fertilizer or agricultural chemical with water. As the spreading agent, for example, there is generally used a polyoxyethylene alkyl phenyl ether, a polyoxyethylene alkyl ether, a polyoxyethylene fatty acid ester, a lignin sulfonate, or a naphthylmethanesulfonate, which has a property of reducing the surface tension of a spray liquid to improve adhesion ability or spreadability to a hardly wetted mite's body or crop plant and to enhance an effect of the fertilizer or agricultural chemical. However, the agents have very high affinity to water, and hence the runoff of the agents due to rainfall cannot be suppressed.
Some of spreading agents exhibiting fixation effects contain a polyoxyethylene resin acid ester, paraffin, or the like as a major component, but have problems in that the effects of the agents cannot be exhibited when the agents are used at low concentrations, and in that films formed by drying the agents are not dissolved in water and hence remain forever on plants. The spreading agents further have problems in that the agents are poorly soluble in the above-mentioned solutions diluted with water and act only when blended in large amounts.
In recent years, a fixable composition of an agrochemical active component containing a polyvinyl alcohol has been developed to solve the above-mentioned problems (see Patent Document 1).